In recent years, demand for a camera (stereoscopic imaging apparatus) that is capable of photographing a 3D (stereoscopic) image has increased. As an imaging method of a stereoscopic image, a beam splitter type (a half mirror type) that performs the photographing by using a half mirror, a side-by-side type (a type for two eyes in parallel) that performs the photographing using two imaging apparatuses that are physically parallel with each other, or the like are disclosed. In such photographing types, an imaging apparatus is mounted on a stand called a rig and performs the photographing, so that a degree of freedom of mounting the imaging apparatus increases. For example, an inter-lens distance (base line length; hereinafter, referred to as “IAD: Inter Axial Distance”) of two lenses that are used for photographing the stereoscopic image, convergence, an angle of view, or the like may be selected with a high degree of freedom.
While the degree of freedom is high, there is a problem in that to mount the imaging apparatus on the rig, a lot of effort and time are necessary for setting and adjustment for each photographing. In addition, particularly, the beam splitter type rig becomes a significantly large-scale apparatus, so that there is a problem in that this rig is not appropriate to use for photographing or for interviews in the field.
To solve such a problem, two 2D image photographing cameras that perform the photographing in the side-by-side method are accommodated in a single casing to configure an integral two-eye 3D camera. The integral two-eye 3D camera configured in this way does not need to be assembled, and adjustment of alignment is also not necessary. In addition, due to the compact structure, even in the case of photographing or interviews in the field, there is an advantage in that it is easy to be carried and setup is made within a short time, so that photographing can be started immediately.
However, basically, such an integral two-eye 3D camera is a side-by-side type, so that there is a limit for adjustment of IAD. That is, optical systems or imagers of the two eyes physically interfere with each other, so that it is difficult to make IAD shorter than a constant distance determined by a dispositional position of the optical systems or the imagers. Therefore, for example, in the case of performing the photographing at a position that is very close to a subject, a parallax at the time of displaying on a 3D display located at a position of substantially several meters behind the subject exceeds a parallax range allowing people to comfortably view a 3D image.
As a case where the distance between the subject and the imaging apparatus is very short, for example, interview photographing of a person or photographing at the time of sport relay broadcasting in a backyard may be considered. In this case, the distance between the subject and the imaging apparatus is substantially 1 to 2 m, a convergence point is adjusted to a distance of 1 to 2 m. The most useful IAD in this case, which allows a parallax to be within a range in which people can comfortably view a 3D image, is 10 to 40 mm. However, in present integral two-eye 3D cameras, it is difficult to realize such a short IAD while maintaining image quality and functions, that is, without making a diameter of a lens or a size of the imager small.
In the case of performing the photographing with the above-described beam splitter type, two imaging apparatuses do not physically interfere with each other, so that it is possible to make IAD very short. However, as described above, there is a problem in that a lot of effort and time are necessary for setting and adjustment for each photographing. Therefore, there is still a problem in that this beam splitter type is not appropriate for interview photographing of a person or photographing at the time of sport relay broadcasting in a backyard.
For example, in JP-A-2003-5313, there is disclosed a stereoscopic imaging apparatus that is capable of adjusting the convergence point to an arbitrary position while a focus point of a camera is coincident with the convergence point of two eyes. When using this apparatus, it is possible to perform the photographing in a state where IAD is made to be the same as a pupil distance. Therefore, even when performing the photographing in the proximity of the subject, it is possible to photograph images from which a natural stereoscopic effect can be obtained.